Combustion, halogenation, oxidation and dehydration of alcohols

38. understand the reactions of alcohols with:

i oxygen in air (combustion)

ii halogenating agents:

• PCl₅ to produce chloroalkanes

• 50% concentrated sulfuric acid and potassium bromide to produce bromoalkanes

• red phosphorus and iodine to produce iodoalkanes

iii potassium dichromate(VI) in dilute sulfuric acid to oxidise primary alcohols to aldehydes (including a test for the aldehyde using Benedict’s/Fehling’s solution) and carboxylic acids, and secondary alcohols to ketones In equations, the oxidising agent can be represented as [O].

iv concentrated phosphoric acid to form alkenes by elimination Descriptions of the mechanisms of these reactions are not expected.